Keith Griffiths is chairman, design leader and founder of Aedas. He is an internationally respected architect and planner and has a deep understanding of the growth of major cities and their changing markets, society and culture. Here, he talks about how property owners and developers can incorporate green-building features. Are Hong Kong developers and property owners keen to incorporate green-building features? What benefits can you as the architect offer? Many developers in Hong Kong are keen to incorporate green elements into their projects as these assists in marketing their developments. The Hong Kong government also provides incentives to use green features. However, there has been a decreasing use of green features in recent years as some of the incentives, which were available in the early 2000s, no longer exist. Some present green features include balconies for residential buildings, wider common corridors and lift lobbies for residential buildings, communal sky gardens for residential buildings, communal podium gardens for non-residential buildings, acoustic fins, wing walls, wind catchers and funnels. As one of the world’s leading architecture and design practices, Aedas promotes green architecture. Saving energy by an insulated building envelope is one example. In Hong Kong, buildings account for 90 per cent of the total electricity consumption [or 60 per cent of carbon emission], in which 26 per cent of electrical energy is consumed by residential buildings. The use of triple-glazed thermal break windows with trickle ventilation and external wall insulation can effectively reduce around 50 per cent of the air conditioning energy consumption. What are the latest trends in green-building design and construction? Western countries increasingly adopt factory-modularised bathrooms, kitchens and plant rooms for residential spaces. In Hong Kong, modular and standardised components in building design are also increasingly applied for enhancing buildability and reducing construction waste. The components may include structural elements, precast façade, internal wall panels and building services elements. Architects should keep in mind the use of standardised grid systems of design allowing standard-sized factory-built and assembled components to be used. What are the challenges or constraints when incorporating sustainability in the design of green buildings in Hong Kong, especially since the city is a very densely built environment ? The biggest challenge in Hong Kong is the government’s use of gross-floor-area measurement allied to very high costs of land to the developers. This discourages developers from using thick and highly-insulated external walls, wide naturally-ventilated access corridors and better residential planning other than cruciform blocks. Hong Kong’s residential buildings will become more efficient with lower energy and carbon consumption if the government creates a more sophisticated method of measuring the value of land. What is passive design? What are net-zero, or even positive-energy, buildings? Can they be built in Hong Kong? Passive design refers to making good use of the surrounding natural context to create favourable internal environmental conditions. Examples are the use of a glazed conservatory system to provide a buffer room for heating in winter and cooling in summer; insulation to external walls and roof to allow the building structure to reserve heat; appropriate building orientation to avoid the hot western sun; cross ventilation between buildings to minimise the use of air conditioning. Enhancing urban air ventilation and building permeability is an effective passive design. Site planning is one of the major factors affecting the urban microclimate. Architects should carry out microclimate study during the early design stage quantifying the air ventilation performance in the vicinity of the development, taking advantage of the existing localised breeze, designing new wind corridors, and optimising the designs of site layout and building massing. Computational Fluid Dynamics brings designers a new dimension of tool to visualise wind effect and to evaluate ventilation performance of the design. Solar radiation is the direct component which increases the cooling load of a building.